Thus, we say, the ultimate need for a theory that in some way unifies QM and GR—a theory of quantum gravity (QG)— arises from the existence of phenomena in our universe in which the domains of the two overlap. There are other, more theoretical, arguments for such a theory and concerning the form it should take. For a critical evaluation of these, arguing that overlap is best reason to seek quantum gravity, and that empirical considerations best dictate its form see [1]}; for further discussion [2]}.This situation may change if the technology improves enough over the next few years to carry out the experiment proposed by [3]}.
